The invention relates to a charge transfer device comprising a series of similar semiconductor cells each having an input, an output and a capacitance for the storage of a charge which represents information and at least one control electrode for charge-transfer, the input of substantially each cell being coupled to the output of the preceding cell and control means being provided for applying clock signals to the control electrodes of consecutive cells in accordance with a cyclic permutation in order to control the charge transfer in the charge transfer device.
Charge transfer devices of the aforementioned type are inter alia known from U.S. Pat. No. 3,666,972. These devices have the drawback that during transfer of a signal charge packet from one cell of the charge transfer device to a following cell a residual charge remains in the first-mentioned cell, so that firstly the magnitude of the charge packet transfer decreases and secondly the residual charge is added to a following signal charge packet which passes through. Obviously, the first effect can be overcome by linear amplification of the attenuated signal charge packet. However, the second effect gives rise to "smearing" of the signal charge packet, so that the next signal charge packet is distorted under the influence of its predecessor. A description of this problem can be found in the report of the "Third International Conference on the Technology and Application of Charge Coupled Devices" held in September 1976 at Edingburgh, in an article by Chowaniec and Hobson on pages 227-231, entitled: "An Analysis of CCD Recursive Filters with Application to MTI Radar Filters."
Until now solutions to the smearing problem were directed to improving the basic cell itself, but this gives rise to complications, because such an improvement should be applied as many times as the number of cells contained in the charge transfer device.